The use of surveillance systems for remotely monitoring and/or recording images for later viewing has been used for many years since the invention of basic television apparatus. Such equipment is used to monitor and/or record information concerning the identity of personnel entering restricted areas in a wide variety of applications. One of the most common uses of such surveillance equipment is to monitor retail sales outlets including, but not limited to, check-out stations where a customer exchanges money for goods in making a retail purchase. In particular, problems of theft, shoplifting and the like, have had severe impacts on the cost of goods in the United States. Losses suffered by retail sales outlets from shoplifting and other forms of theft are eventually passed on to the consumer in the form of higher prices. The retail operator who can successfully reduce its shoplifting and theft losses has a significant advantage over its competitors in that the same profit margins can be obtained while charging the customer lower prices.
A significant form of theft suffered by retailers is that known as "under-ringing". This involves a conspiratorial arrangement between an employee of the retail outlet and a third person. It is executed by having a third person bring goods to a check-out station, which includes a cash register, staffed by a dishonest employee. The employee operating the cash register will ring up charges that are below the actual price of the goods in question. The goods will be appropriately wrapped or bagged, and the third party will leave the store after having paid only a fraction of the actual price of the goods.
To the casual observer, the transaction between the dishonest employee and the third party is in all respects normal, goods are passing by the check-out stand, prices are being rung up and money exchanges hands. It has been known in the prior art for some period of time to monitor amounts rung on electronic cash registers while, at the same time, observing through a video monitor (either in real time or reviewing a tape of a transaction) the goods passing the check-out stand.
Also, surveillance systems have been widely used in retail outlets, banks and other locations to aid in apprehending criminals conducting a less subtle form of theft, such as armed robbery. For example, it has been known in the art to have either "panic button" alarm switches, or drawer switches in a cash register drawer wherein a particular piece of currency or the like is never to be removed in normal operation. Application of the panic button switch is apparent.
In the latter example, the piece of currency or the like will have an insulating property between two conductive contact materials which appear to the observer to be normal weighed levers for holding currency in place in a cash drawer. Upon the occurrence of a theft, the employee is instructed to pull all of the bills from the slot containing the special contacts and an alarm signal is produced causing one of several events to occur. Normally the event will be either the turning on of a video tape recorder to which a monitoring camera is attached, a change of mode of the video recorder from a lapsed time mode to a real time mode, or the like. One prior art system uses a continuous loop recorder, thus providing a predetermined "time window" of real time recording. Upon the receipt of such an alarm condition, recording terminates after a predetermined period of time so that a record of the event which caused the alarm condition will be maintained, rather than being erased as the continuous loop recycles through the recorder.
All of these devices have proved useful for their intended purpose. However, experience has shown that it is difficult to design a surveillance system which fully takes into account common phenomena of human behavior and perception so that the maximum amount of useful and important information is recorded in a fashion in which it will not be inadvertently ignored by a person monitoring the information, either in real time or during some form of playback at a later time. Thus, the basic problem of designing a surveillance system having the maximum possible utility is one of designing event detection apparatus which will activate recorders, change a mode of recording, or change the nature of a video real time display, to attract the attention of the person monitoring the events. This may be generically thought of as a design problem for properly scaling and defining the alarm events which cause one of the aforementioned responses (recording, changing recorder mode, or changing the nature of the video display) to occur.
Needless to say, the problem of collecting all possible information about occurrences in a monitored area is technically trivial. All one needs to do is provide an appropriate number of cameras, an appropriate number of recorders, and turn all of them on in a real time mode so that all possible events are recorded. This is impractical for reasons of cost, and the fact that nothing is particularly brought to the attention of a person monitoring such a system. In other words, the indiscriminate recording of all information is hardly an improvement over having a person simply standing in the monitored area.
Thus, the problem of designing a useful surveillance system becomes one of defining the conditions which will be considered an alarm event to either turn on a recorder or change a display so that the event is brought to the attention of the monitoring person. If events are defined so that a large number of alarm events in the system occur when experience shows that very few of these events are either out of the ordinary or cause for concern, the monitoring party naturally becomes insensitive to the events. In other words, multiple repetitions of events which should not cause concern to the operators of the retail outlet will quickly cause them to lose interest in monitoring each of the recorded alarm events. For example, if the camera is turned every time a cash register drawer is opened (opening of the drawer being the only criteria), it can become quite tiresome to monitor a very large number of normal transactions looking for something out of the ordinary. Experience has shown that the natural tendency of persons monitoring such a display is to become inattentive, and an event which is out of the ordinary or problematic can be missed. At the other extreme, the conditions defining an alarm event should not be so severe that there is a high probability that an event which should be recorded or monitored will be missed.
The surveillance system of the present invention is particularly suited for use in retail outlets, although it can be used in a wide variety of applications. Prior art systems designed to be used in retail outlets have been directed almost exclusively to monitoring thefts, either some form of employee dishonesty or some form of robbery by a third party. Prior art surveillance systems have not addressed the ability of such a system to monitor events which fall outside the standard operating procedures, even though no dishonest act may be occurring. Furthermore, prior art systems have not been designed with alarm events defined that may be extremely useful in gathering data on pertinent behavior of store employees. This may be used to define appropriate standard operating procedures or identify dangerous situations which do not necessarily involve employee dishonesty.
This type of problem can become extremely acute in an environment such as a convenience store which is often operated by a single employee during periods of the early morning or late evening when there is a low amount of customer traffic. Proper procedures by employees at check-out stands in such retail operations are essential to prevent mistakes on the part of the employee, deception on the part of the customer, and theft. For example, a number of dishonest people, given the opportunity, will lie to a store employee concerning the amount tendered if proper procedures for ringing up the amount tendered, and handling of the currency actually tendered to the casher, are not followed. Similarly, many thieves are aware of the fact that prison sentences for armed robbery are much more severe than those for other forms of theft, and wil grab money from an open cash drawer and quickly exit the establishment if the opportunity presents itself, but they will not resort to the use of weapons.
Also, under many conditions of operation of a small retail establishment, knowledge of the number of people either in the store at a particular time, or the total number of people who have entered the store during a period of elapsed time, can become imporatant in monitoring store receipts and video signals for detection of employee dishonesty. Prior art surveillance systems have attempted to approximate this solely by using switches which detect openings and closures of a door into the establishment. Common experience teaches that the relationship between the number of openings and closures of an entrance door and the number of people in the store can vary widely. For example, if a group of three or four people enter a convenience store at one time, this will often be accomplished with only one opening of the entrance door, while all the people pass through, the last person allowing the door to shut. Furthermore, experience has taught that, in the convenience store environment, the entry of three or four people into the store at one time is a condition which ought to be watched carefully. A number of dishonest people will often conspire to shoplift by arranging to have one or two people occupy the attention of the cashier while other members of the party abscond with the goods.
If cameras are turned on every time there is a door opening or closure, the aforementioned problem of recording too much information will often be presented. Furthermore, merely counting door closures does not give reliable information as to the accumulated number of people who may be on the premises at any one time. For example, detection of a door opening and closing might indicate to a surveillance system that a single customer had entered. Some time later, another opening and closure may be detected. In the prior art systems, it is virtually impossible to ascertain whether the first customer has left, leaving the store empty of customers, or whether a second customer (or a plurality of additional customers) has entered the premises.
In summary, there is a need in the prior art for providing a surveillance system in which alarm events are defined so that they are useful, not only for detecting theft problems, but also for gathering data, and monitoring the procedures executed by employees. This information can serve as an effective management tool for the operation of the establishment in which the system is placed. There is a further need to provide such a system in which the alarm events are defined so that only events which are out of the ordinary or fall outside a predefined procedure are recorded in real time or fully displayed on a monitor.
There is a further need in the art of surveillance systems to provide a surveillance system which can more accurately monitor the net number of customers or potential customers within the establishment in a manner which is more accurate than counting door openings and closures.